Two Boston hospitals are reviewing their approach to a surgical technique commonly used in hysterectomies following two medical cases that have led to debate on the potential cancer risks associated with the procedure.

The technique, called morcellation, is characterized by a surgeon shredding tissue, usually fibroids or the uterus, during a laprascopic hysterectomy that is then usually removed through a small incision in the abdomen.

Both Massachusetts General Hospital and Brigham and Women's Hospital in Boston are revising their guidelines and informed consent policies regarding the procedure.

Both hospitals are making changes in part due to two medical cases in which women had undetected cancer spread into their abdomen following the procedure.

One woman, Dr. Amy Reed, 41, is an anesthesiologist at Beth-Israel Hospital in Boston. Now suffering from stage IV cancer, Reed and her husband, Dr. Hooman Noorchashm, a cardiothoracic surgeon at Brigham and Women's, have started a Change.org petition and written letters to try and stop doctors from performing the procedure because they say it is too dangerous.

Medical experts say that the procedure has long been appealing to patients because a laparoscopic hysterectomy with morcellation means a faster healing time for patients and minimal scaring, compared to an abdominal hysterectomy, which involves opening the abdominal cavity.

The American College of Obstetrics and Gynecology (ACOG) said that the chance of spreading the virulent and deadly cancer, leiomyosarcoma, through morcellation is "rare." However, the ACOG said the risk for other cancers spreading through morcellation is not clearly known.

According to ACOG, 498,000 hysterectomies were performed in the U.S. in 2010 and the chance of discovering leiomyosarcoma through surgery is 1 in 2000.

Many women, including Reed, have hysterectomies due to uterine fibriods that can cause irregular menstrual bleeding, pelvic pressure or pain.

Sometimes doctors are able to just break up and remove fibroids and leave the uterus intact by using morcellation in a similar laparoscopic procedure.

Dr. Robert Barbieri, the chief of obstetrics and gynecology at Brigham and Women's, said doctors at the hospital would now discuss with patients that if they have undetected cancer the morcellation procedure can cause the cancer to spread.

Barbieri said the changes were made in part because of two cases at the hospital, including Reed's, over the last 14 months.

In a memo issued to medical staff, Barbieri said that the best estimate for how often cancerous or atypical cells are spread through the procedure is "as many as 1 in 400 cases or as infrequently as less than 1 in 1,000 cases."

In addition, Barbieri said the hospital would now recommend staff not perform morcellations in women at a higher risk for having undetected cancer, such as women in a certain age group.

"I don't think it's right to ban all morcellation," said Barbieri. "In a 25-year-old or a 30-year-old the chance of having a sarcoma [cancer] is extremely low. I would worry about a 50-year-old."

Citing a 2012 study published in the Public Library of Science, Barbieri said that in 1,091 morcellation procedures performed at Brigham and Women's over five years, only one woman was found to have leiomyosarcoma, the same virulent undetected cancer as Reed's.

However, that study did find that the rate of finding unexpected cancer after the morcellation procedure was 0.09 percent. While small, that percentage is "9-fold higher than the rate currently quoted to patients during pre-procedure briefing," according to the study.

At Massachusetts General Hospital, Dr. Isaac Schiff, chair of obstetrics and gynecology, said they have revised their guidelines around informed consent for the morcellation procedure so that patients have more information.